HDAC6 and Parkinson disease: Among 18 different members of the histone deacetylase family in humans, sharing the common deacetylation substrate, microtubule-associated tubulin, HDAC6 and SIRT2 are predominant in the cytoplasm and play significant roles in a variety of neurodegenerative disorders, which make these two isoforms become most attractive targets for treating neurodegenerative diseases, including Parkinson’s disease.